Biotransformation of a C-glycosylflavone, abrusin 2''-O-beta-D-apioside, by human intestinal bacteria

After anaerobic incubation of abrusin 2'-O-beta-D-apioside (1) with a human fecal suspension, five metabolites were isolated and identified as abrusin (2), 1-(2',6'-dihydroxy-3',4'-dimethoxyphenyl)-3-(4'-hydroxyphenyl)propan-1- one (5), 5,6-dimethoxybenzene-1,3-diol (6), 3-(4'-hydroxyphenyl)propionic acid (7) and 3-phenylpropionic acid (8). However, methyl ether derivatives of abrusin (4'-O-methylabrusin and 4'-O-, 5-O-dimethylabrusin) resisted degradation under the same conditions.     

Synthesis of polymer-bound 4-acetoxy-3-phenylbenzaldehyde derivatives: applications in solid-phase organic synthesis

Aminomethyl polystyrene resin was reacted with 4-(5'-formyl-2'-hydroxyphenyl)benzoic acid and 4-(5'-formyl-2'-hydroxyphenyl)phenyl propionic acid, respectively, in the presence of 1-hydroxybenzotriazole and 1,3-diisopropylcarbodiimide to yield polymer-bound benzaldehydes. The phenolic group in resins was acetylated with acetic anhydride to afford two polymer-bound 4-acetoxybenzaldehydes. The reductive amination of polymer-bound linkers by amines and sodium triacetoxyborohydride, followed by sulfonylation with arylsulfonyl chloride derivatives in the presence of pyridine and the cleavage with TFA/DCM/H2O, produced pure sulfonamides.     

New sesquiterpenes and calebin derivatives from Curcuma longa

One novel sesquiterpene with new skeleton, (6S)-2-methyl-6-(4-hydroxyphenyl-3-methyl)-2-hepten-4-one (1), two new bisabolane sesquiterpenes, (6S)-2-methyl-6-(4-hydroxyphenyl)-2-hepten-4-one (2), (6S)-2-methyl-6-(4-formylphenyl)-2-hepten-4-one (3), and two calebin derivatives, 4'-(4'-hydroxyphenyl-3'-methoxy)-2'-oxo-3'-butenyl-3-(4'-hydroxyphenyl)-propenoate (4) and 4'-(4'-hydroxyphenyl)-2'-oxo-3'-butenyl-3-(4'-hydroxyphenyl-3'-methoxy)-propenoate (5) were isolated along with five known bisabolane sesquiterpenes from Curcuma longa. 1-4 were new compounds and 5 was a new natural product. Their structures were established by spectral methods.     

NEW FEATURES IN THE PHOTOPHYSICS and PHOTOCHEMISTRY OF 2-(2''-HYDROXY-PHENYL)BENZOTHIAZOLES INTRODUCED BY AMINE SUBSTITUTION

The photophysics and photochemistry of the 4'-diethylamino derivative of both 2-phenyl-benzothiazole and 2-(2'-hydroxyphenyl)benzothiazole have been studied by nanosecond and microsecond laser flash photolysis and picosecond emission spectroscopy. For the non-hydroxy substituted molecule, the singlet excited state was shown to relax primarily via fluorescence emission, and a very weak triplet transient was observed after laser flash excitation. The 2-(2'-hydroxy-4'-diethylaminophenyl)benzothiazole (AHBT) was shown to undergo excited state intramolecular proton transfer (ESIPT) in the picosecond timescale (k greater than 3 x 10(10) s-1) to form a colored zwitter-ion/keto form in solution at room temperature while the ground state back proton transfer was slower by a factor of approximately 10(5). However, in marked contrast with other derivatives of 2-(2'-hydroxyphenyl)benzothiazole and related molecules, the ESIPT was not the only deactivation process of the lowest singlet excited state of the enol form. Under steady-state excitation at room temperature (and low temperature), the fluorescence emission of the enol form was observed. The T-T absorption of the enol form was also observed and furthermore, the ESIPT was shown to have an activation energy which was estimated to be approximately 4 kJ. None of the foregoing, fluorescence and T-T absorption of the enol nor activation energy for proton transfer have been observed for the parent or derivatives of 2-(2'-hydroxyphenyl)benzothiazoles. The striking new features for the ESIPT photochemistry and photophysics for the 4'-diethylamino derivative of 2-(2'-hydroxyphenyl)benzothiazole are discussed and MO calculations are used to aid in the interpretation of some of the experimental results.     

Rotamerism, tautomerism, and excited-state intramolecular proton transfer in 2-(4'-N,N-diethylamino-2'-hydroxyphenyl)benzimidazoles: novel benzimidazoles undergoing excited-state intramolecular coupled proton and charge transfer

The solvent and temperature dependence of the phototautomerization of 1-methyl-2-(2'-hydroxyphenyl)benzimidazole (4) and the novel compounds 2-(4'-amino-2'-hydroxyphenyl)benzimidazole (1), 2-(4'-N,N-diethylamino-2'-hydroxyphenyl)benzimidazole (2), and 1-methyl-2-(4'-N,N-diethylamino-2'-hydroxyphenyl)benzimidazole (3), together with the ground-state rotamerism and tautomerism of these new compounds, have been studied by UV-vis absorption spectroscopy and steady-state and time-resolved fluorescence spectroscopy. A solvent-modulated rotameric and tautomeric equilibrium is observed in the ground state for 1, 2, and 3. In cyclohexane, these compounds mainly exist as a planar syn normal form, with the hydroxyl group hydrogen-bonded to the benzimidazole N3. In ethanol, the syn form is in equilibrium with its planar anti rotamer (for 1 and 2), with the phenyl ring rotated 180 degrees about the C2-C1' bond and with a nonplanar rotamer for compound 3. In aqueous solution, a tautomeric equilibrium is established between the anti normal form (or the nonplanar rotamer for 3) and the tautomer (with the hydroxyl proton transferred to the benzimidazole N3). The syn normal form of these compounds undergoes in all the solvents an excited-state intramolecular proton-transfer process from the hydroxyl group to the benzimidazole N3 to yield the excited tautomer. The tautomer fluorescence quantum yield of 2, 3, and 4 shows a temperature-, polarity-, and viscosity-dependent radiationless deactivation, connected with a large-amplitude conformational motion. We conclude that this excited-state conformational change experienced by the tautomer is associated with an intramolecular charge transfer from the deprotonated dialkylaminophenol or phenol (donor) to the protonated benzimidazole (acceptor), affording a nonfluorescent charge-transfer tautomer. Therefore, these compounds undergo an excited-state intramolecular coupled proton- and charge-transfer process.     

NaCu(II)4] cluster from alkali template assembly of two asymmetric end-on azido-bridged [Cu(II)2] units

The cluster [NaCu4L2(N3)2](ClO4) [1; H3L is 2-(2'-hydroxyphenyl)-1,3-bis[3'-aza-4'-(2'-hydroxyphenyl)prop-4'-en-1'-yl]-1,3-imidazolidine] has been synthesized and structurally characterized. Complex 1 is formed by the template assembly of two [Cu2L(N3)] neutral fragments through their weak oxophilic interactions with a central Na+ cation as observed in metallacrowns. The cluster exhibits a combination of ferro- and antiferromagnetic interactions. End-on N3- bridging of copper ions within the [Cu(II)2] units facilitates stabilization of S = 1 magnetic subunits that mutually cancel via antiferromagnetic coupling as mediated by the O...Na+...O bridges.     

Tautomerization in gas-phase ion chemistry of isomeric C-8 deoxyguanosine adducts from phenol-induced DNA damage

Collision-induced dissociation (CID) of 8-(4'-hydroxyphenyl)-2'-deoxyguanosine and 8-(2'-hydroxyphenyl)-2'-deoxyguanosine was investigated using sequential tandem mass spectrometry. These adducts represent biomarkers of DNA damage linked to phenolic radicals and were investigated to gain insight into the effects of chemical structure of a C-8 modification on fragmentation pathways of modified 2'-deoxyguanosine (dG). CID in MS(2) of the deprotonated molecules of both the isomers generated the same product ion having the same m/z values. CID in MS(3) of the product ion at m/z 242 and CID in MS(4) experiments carried out on the selected product ions at m/z 225 and m/z 218 afford distinct fragmentation patterns. The conformational properties of isomeric product ions from CID showed that the ortho-isomers possess the unique ability to tautomerize through an intramolecular proton transfer between the phenolic OH group and the imine nitrogen (N7). Tautomerization of ortho-isomers to their keto-tautomers led to differences in their system of conjugated double bonds compared with either their enol-tautomer or the para-isomer. The charge redistribution through the N-7 site on the imidazole ring is a critical step in guanosine adduct fragmentation which is disrupted by the formation of the keto-tautomer. For this reason, different reaction pathways are observed for 8-(4'-hydroxyphenyl)-2'-deoxyguanosine and 8-(2'-hydroxyphenyl)-2'-deoxyguanosine. We present herein the dissociation and the gas-phase ion-molecule reactions for highly conjugated ions involved in the CID ion chemistry of the investigated adducts. These will be useful for those using tandem mass spectrometry for structural elucidation of C-8 modified dG adducts. This study demonstrates that the modification at the C-8 site of dG has the potential to significantly alter the reactivity of adducts. We also show the ability of tandem mass spectrometry to completely differentiate between the isomeric dG adducts investigated.     

Generation of an equilibrating collection of crystalline solids from a dynamic combinational library

Thermodynamically controlled crystallization of a copper-containing building block [CuL] (H(2)L = 2-(2'-hydroxyphenyl)-Delta(2)-thiazoline-4-carboxylic acid) from a methanol-ethanol mixture solvent leads to a combinatorial mixture of four crystalline solids, from which each of them is isolated and structurally characterized.     

3-对甲氧基苯基-和3-对羟基苯基-1-氨基-3a,4,5,9b-四氢化-9b-羟基-3H-环戊烯并[a]萘-2-甲腈的合成和晶体结构

用低价钛试剂(TiCl₄-Zn)与2-氰基-3-对甲氧基苯基-3-(1-四氢萘酮-2-基)丙腈反应合成了3-对甲氧基苯基-1-氨 基-3a,4,5,9b-四氢化-9b-羟基-3H-环戊烯并[a]萘-2-甲腈和3-对羟基苯基-1-氨基-3a,4,5,9b-四氢化-9b-羟基-3H-环戊烯并[a]萘-2-甲腈, 并用X射线衍射分析确定了这两个产物的结构.     

New diarylheptanoids from Amomum muricarpum ELMER

Two new diarylheptanoids, designated muricarpones A and B, together with three known diarylheptanoids, 1,7-di-(3',4'-dihydroxyphenyl)-4-hepten-3-one, 1-(3',4'-dihydroxyphenyl)-7-(4'-hydroxyphenyl)-4-hepten-3-one, and 1,7-bis(p-hydroxyphenyl)-4-hepten-3-one, were isolated from the rhizomes of Amomum muricarpum ELMER (Zingiberaceae). Their structures were determined using spectroscopic analyses.     

Flavonoid constituents from the roots of Acanthopanax brachypus

Two new natural products, (3R)-5,7-dihydroxy-8-(2″-O-veratroyl-β-D-glucopyranosyl)-3-(4'-hydroxyphenyl)-6-methylchroman-4-one (1) and 4'-hydroxyisoflavone-7-O-[α-L-arabinopyranosyl-(1→6)-β-D-glucopyranoside] (2), along with eleven other known flavonoids, were isolated from the roots of Acanthopanax brachypus. Their structures were elucidated on the basis of spectroscopic and chemical evidence.     

New phenylalkanoids from Zingiber officinale

Two new phenylalkanoids, 3-hydroxy-1-(4'-hydroxy-3'-methoxy-phenyl)-hexan-5-one (1) and 3-hydroxy-1-(3',5'-dimethoxy-4'-hydroxyphenyl)-hexan-5-one (2) were isolated from the rhizomes of Chinese ginger (Zingiber officinale Roscoe (Zingiberaceae)). The structures of two new phenylalkanoids were elucidated by chemical and physical evidence.     

Fluorimetric determination of hydrogen peroxide by use of the fluorescence reaction between N-(4'-hydroxyphenyl)-N-(4-methylquinolinyl)amine and cobalt(II) in the presence of trimethylstearylammonium chloride

The fluorimetric determination of hydrogen peroxide by using the fluorescence reaction between N-(4'-hydroxyphenyl)-N-(4-methylquinolinyl)amine (HPMQ), cobalt(II) and hydrogen peroxide in the presence of trimethylstearylammonium chloride (STAC) as a cationic surfactant was proposed. The calibration graph was linear in the range 0-2500 ng of hydrogen peroxide per 10 ml of solution at an emission wavelength of 522 nm with excitation at 410 nm. The recovery tests in foods were good.     

An efficient chloride-selective fluorescent chemosensor based on 2,9-bis(4'-hydroxyphenyl)phenanthroline Cu(II) complex

A new complex Cu(II)/L, composed of 2,9-bis(4'-hydroxyphenyl)phenanthroline (L) and Cu(II), was synthesized as an efficient chloride-detection fluorescent chemosensor with high selectivity and sensitivity over other halide anions, F(-), Br(-), I(-). The recognition mechanism was discussed primarily.     

Structures of 4-aryl-coumarin (neoflavone) dimers isolated from Pistacia chinensis BUNGE and their estrogen-like activity

Activity-guided fractionation of twigs of Pistacia chinensis resulted in the isolation and characterization of two novel ingredients as potent estrogen agonists. On the basis of spectral analysis and comparison with a related compound their structures were elucidated as 3,3'-dimers of 4-aryldihydrocoumarins (3,4-dihydro-4-(4'-hydroxyphenyl)-7-hydroxycoumarin) differing only in the stereochemical disposition of the linkage between the two 4-arylcoumarin moieties. These compounds are the first examples of bis-flavonoids which have been proven to possess estrogen-like activity.     

Largamides A-H, unusual cyclic peptides from the marine cyanobacterium Oscillatoria sp

Seven new depsipeptides, termed largamides A-G (1-7), and one new cyclic peptide, largamide H (8), have been isolated from the marine cyanobacterium Oscillatoria sp. Their structures were determined by NMR and ESI-MS techniques. The absolute configurations were assigned using LC-MS, chiral HPLC, and combined analysis of homonuclear and heteronuclear (2,3)J couplings, along with ROE data. Largamides, isolated from a single homogeneous cyanobacterial collection, represent three different structural classes of peptides. Largamides A-C (1-3) are characterized by the unusual occurrence of a senecioic acid unit, while largamides B (2) and C (3) possess in addition the rare 2-amino-5-(4'-hydroxyphenyl)pentanoic acid (Ahppa) and the novel 2-amino-6-(4'-hydroxyphenyl)hexanoic acid (Ahpha), respectively. Largamides D-G (4-7) are the first 3-amino-6-hydroxy-2-piperidone acid (Ahp)-containing depsipeptides reported with the rare Ahppa unit. Largamide H (8) is a unique cyclic peptide displaying a new 2,5-dihydroxylated beta-amino acid moiety, a methoxylated derivative of Ahppa, and two residues of the nonstandard 2,3-dehydro-2-aminobutanoic acid (Dab). Largamides D-G (4-7) inhibited chymotrypsin with IC(50) values ranging between 4 and 25 microM.     

Ultra-performance LC-photodiode array-eλ-ESI-MS/MS screening method for the detection of radical-scavenging natural antioxidants from radix et rhizoma Rhei

A novel ultra-performance LC-photodiode array-el-ESI-MS/MS screening method was developed for the detection and identification of natural antioxidants from radix et rhizoma Rhei. Nine compounds were found to possess a potential antioxidant activity, and their free radical-scavenging capacities were investigated in detail. The nine compounds were identified as 1-O-galloyl-2-O-cinnamoylglucose, 6-hydroxymusizin-8-O-β-D-glucopyranoside, (+)-catechin, gallic acid 3-O-β-D-glucopyranoside, trans-3,5,4'-trihydroxystilbene- 4'-O-β-D-(2"-O-galloyl)-glucopyranoside, sennoside A, 4-(4'-hydroxyphenyl)-2- butanone-4'-O-β-D-(2"-O-galloyl-6"-O-p-coumaroyl) glucopyranoside, emodin-8-O-(6'-Omalonyl) glucopyranoside, and physcion-8-O-β-D-glucopyranoside. The reactivity and SC(50) values of those compounds were investigated, respectively. 1-O-Galloyl-2-O-cinnamoylglucose showed the strongest capability for scavenging 1,1-diphenyl-2-picrylhydrazylfree radical; trans-3,5,4'-trihydroxystilbene-4'-O-β-D-(2"-O-galloyl) glucopyranoside showed the strongest capability for scavenging superoxide radical; 4-(4'-hydroxyphenyl)-2-butanone- 4'-O-2-D-(2"-O-galloyl-6"-O-p-coumaroyl) glucopyranoside exhibited the highest reactivity in the lipid peroxidation processes. The use of the analytical screening method based on ultra-performance LC-photodiode array-el-ESI-MS/MS would provide a new way for rapid detection of radical-scavenging natural compounds from radix et rhizoma Rhei or complex matrices.     

Synthesis and Optical Property of a New Zinc Complex Based on the Derivative of 2-(2'-Hydroxyphenyl)-1H-benzimidazole and Phenanthroline

A novel zinc complex(Zn E) has been designed and synthesized based on the derivative of 2-(2'-hydroxyphenyl)-1-H-benzimidazole(HBI) and the neutral nitrogen-containing ligand(phen). The crystal of the title complex crystallizes in the monoclinic system, space group P21/n with a = 10.2631(2), b = 34.2166(6), c = 11.4103(3) ?, β = 96.771(2)°, Mr = 844.24, V = 3978.99(14) ?3, Z = 4, the final R = 0.0400 and wR = 0.1001 for 8107 observed reflections(I 2σ(I)). In the title complex, the free protonated phenoxide moiety(4-OH) is successfully retained to realize pseudo-intramolecular hydrogen bonds with the coordinated O atom from the other ligand.     

Topological equivalences between organic and coordination polymer crystal structures: an organic ladder formed with three-connected molecular and supramolecular synthons

[structure: see text] Crystal engineering of an organic ladder can be achieved with a T-shaped molecule, 4,4-bis(4'-hydroxyphenyl)-1-cyclohexanol, having three hydroxyl functionalities that can form O-H...O hydrogen-bonded helices. The topology of this network structure finds a parallel in three-connected coordination polymers.     

Amides from the stem of Capsicum annuum

7'-(4'-hydroxyphenyl)-N-[(4-methoxyphenyl)ethyl]propenamide (1), 7'-(3',4'-dihydroxyphenyl)-N-[(4-methoxyphenyl)ethyl]propenamide (2), N-p-trans-coumaroyltyramine (3), N-trans-caffeoyltyramine (4), beta-sitostenone (5), ferulic acid (6), hydroferulic acid (7), 5-hydroxy-3,4-dimethoxycinnamic acid (8), veratic acid (9), vanillic acid (10), isovanillic acid (11), syringic acid (12), (+)-syringaresinol (13), and pheophorbide a (14) were isolated from the stems of Capsicum annuum (Solanaceae). Among them, 1 is a new amide compound. The structures of these compounds were characterized and identified by spectral analyses.